In order to minimize the transmission of interfering vibrations, optical assemblies, in particular projection objectives, are isolated from vibrations. Furthermore, the individual elements within the assemblies are interconnected rigidly (with high natural frequency) in such a way that they move with one another as a rigid body under the excitation of any remaining, usually low-frequency vibrations.
A dynamic separation/decoupling or vibrational decoupling of optical elements of an optical assembly whose positioning relative to the other optical elements poses less stringent requirements would be advantageous, chiefly whenever the additional introduction of interfering vibrations owing to these optical elements is likely, because they can, if appropriate, be manipulated via actuators, motors or the like.
Furthermore, it would be conceivable to fashion specific optical elements to be interchangeable, in order, for example, to be able to vary their optical properties or replace them with other ones. It would thereby be possible to provide a type of interchange mechanism at the optical assembly in order to interchange the optical elements.
The following particular problems arise in this case: it is difficult to use such an interchange mechanism to position the interchangeable optical element in the beam path of the optical assembly with sufficient accuracy and reproducibly. Moreover, the aim should be to avoid transmitting interfering vibrations through this interchange mechanism and the interchangeable optical element onto the optical assembly. A further problem is the contamination of the optical assembly or its individual optical elements by particles which would be produced by the interchange mechanism.